From: Peter Zijlstra <peterz@infradead.org>
To: David Laight <david.laight.linux@gmail.com>
Cc: "Borislav Betkov" <bp@alien8.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Thomas Gleinxer" <tglx@linutronix.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
x86@kernel.org, "Andrew Morton" <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
"Nicolas Pitre" <npitre@baylibre.com>,
"H. Peter Anvin" <hpa@zytor.com>,
"Uwe Kleine-König" <u.kleine-koenig@baylibre.com>,
rodrigo.alencar@analog.com, jic23@kernel.org
Subject: Re: [PATCH 2/2] x86/local: local_add/local_sub: Support large immediate values
Date: Mon, 3 Aug 2026 12:01:14 +0200 [thread overview]
Message-ID: <20260803100114.GG49951@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20260803094702.3852-3-david.laight.linux@gmail.com>
On Mon, Aug 03, 2026 at 10:47:02AM +0100, David Laight wrote:
> Replace the "ir" constraint with "er" so that constants over 2^31
> get loaded into a register.
>
> Signed-off-by: David Laight <david.laight.linux@gmail.com>
> ---
> arch/x86/include/asm/local.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/local.h b/arch/x86/include/asm/local.h
> index 4957018fef3e..68af7b74450a 100644
> --- a/arch/x86/include/asm/local.h
> +++ b/arch/x86/include/asm/local.h
> @@ -32,14 +32,14 @@ static inline void local_add(long i, local_t *l)
> {
> asm volatile(_ASM_ADD "%1,%0"
> : "+m" (l->a.counter)
> - : "ir" (i));
> + : "er" (i));
> }
>
> static inline void local_sub(long i, local_t *l)
> {
> asm volatile(_ASM_SUB "%1,%0"
> : "+m" (l->a.counter)
> - : "ir" (i));
> + : "er" (i));
> }
And the other two sites already have "er", how inconsistent :/
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
next prev parent reply other threads:[~2026-08-03 10:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-03 9:47 [PATCH 0/2] x86: Use "er" asm constriant for add/sub David Laight
2026-08-03 9:47 ` [PATCH 1/2] lib: mul_u64_add_u64_div_u64: Fix addition of large constants David Laight
2026-08-03 10:08 ` H. Peter Anvin
2026-08-03 9:47 ` [PATCH 2/2] x86/local: local_add/local_sub: Support large immediate values David Laight
2026-08-03 10:01 ` Peter Zijlstra [this message]
2026-08-03 10:07 ` H. Peter Anvin
2026-08-03 9:59 ` [PATCH 0/2] x86: Use "er" asm constriant for add/sub Peter Zijlstra
2026-08-03 14:49 ` Nicolas Pitre
2026-08-03 15:39 ` David Laight
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